Known techniques related to control of a torque in an internal combustion engine include the one disclosed, for example, in JP-A-2003-301766. In the technique disclosed therein, an indicated torque demand from a driver is calculated using an accelerator pedaling angle value, and a desired air-fuel ratio is determined inside a control apparatus. After this, the indicated torque demand is corrected using torque efficiency with respect to ignition timing and torque efficiency with respect to the desired air-fuel ratio, and a desired throttle angle is further determined from the desired amount of air calculated from the corrected torque. In addition, an air intake delay correction value is calculated from the desired amount of air and the engine speed, then an ignition timing retard angle is calculated from the above-corrected torque and the estimated torque determined by the air intake delay correction value, and final ignition timing is determined from the ignition timing retard angle and the basic ignition timing determined by an intake air amount. Furthermore, a desired fuel injection amount is determined from the intake air amount and the desired air-fuel ratio.
Briefly, the conventional technique disclosed in the above patent application can be described as one in which the throttle angle, the ignition timing, and the fuel injection amount are coordinatively controlled so as to achieve both the indicated torque demand value demanded from the driver, and the desired air-fuel ratio demanded from the inside of the control apparatus.